1. Field of the Invention
This invention relates generally to systems and method for reading data from and writing data to data storage medium by employing the optical recording technology. More particularly, this invention is related to an improved optical data access system. The data access system is implemented in a portable data card drive device and in a high speed subsystem for reading data from and writing data to an optical data card which has a novel data track configuration for storing data with uniform density. Data can be stored for user applications or related to application system configurations.
2. Description of the Prior Art
Conventional technology of reading-writing data on concentric circular data tracks often presents a problem that the data-bit density varies between the outer tracks and the inner tracks. The variable bit density in data storage is due to a geometrical factor that the outer data tracks are much longer in length than the inner tracks. A common practice is to form the inner tracks with a capacity to store the data bit at a higher bit density. A more complicate servo control system implemented with more complex signal-processing algorithms is required due to the variations of data storage density between different data tracks. Additionally, by varying the data storage density from the inner tracks toward the outside tracks, the data transfer rate is also changed in accessing data from the inner tracks then outside tracks. Such variation may also cause difficulties and complications in processing the data. Higher error rates may incur due to these variations between the inner tracks and the outer tracks.
Therefore, a need still exists for an improved data-card drive system to overcome the aforementioned difficulties encountered in the prior art. Specifically, this storage card drive system must provide a uniform density for data storage and a data-card drive system to access the data-storage card. Furthermore, it would be desirable that this system is portable and is also provided with several standardized sizes for processing standardized data-storage cards.
Therefore, an object of the present invention is to provide a data storage-card drive system with a pickup head moving above the data-storage card in rotational movement. The data read-write functions are enabled only for arc-segments of the rotational movement such that the data tracks are arranged as plurality of parallel arcs, e.g., half-circles, to overcome the aforementioned difficulties and limitations encountered in the prior art.
Specifically, it is an object of the present invention to provide a data-storage card drive system with a pickup head driven by a motor, e.g., a brushless motor, to rotate over the data-storage card with the rotation axis perpendicular to the card surface. The motor is mounted on a carriage for making horizontal movement along a longitudinal direction of the data card. The position of the pickup head is then servo-controlled by moving the carriage and the motor while the data storage card either stays at a fixed position or only pickup head is rotating and the card is making horizontal linear movements.
Another object of the present invention is to provide a data-storage card drive system for performing the data access tasks over a data storage medium surface, which has uniform data storage density. A new configuration of data-tracks formed as parallel arc or arc-segments, e.g., semi-circular data track, is implemented such that all data tracks have substantially the same length for data storage and the data bits are stored with uniform density.
Another object of the present invention is to provide a data-storage card drive device implemented with a subsystem provided with local memory storage for conveniently interface with personal computers or peripheral devices to achieve higher speed operations.
Briefly, in a preferred embodiment, the present invention discloses an optical servo writer. The optical servo writer includes an optical pickup head for rotationally moving over and writing servo data in an optical flat data-storage medium. The optical servo writer further includes a clock head for providing clock signals to the pickup head and to write clock signals in clock disk. The optical servo writer further includes a control circuit for controlling the optical pickup head for writing the servo data on the optical flat data-storage medium. The optical servo writer further includes a servo pattern layout circuit for controlling the optical pickup head for writing the servo data on the optical flat data-storage medium with predefined servo patterns. The optical servo writer further includes a derived index control circuit for deriving indices from a fixed index provided on the optical flat data-storage medium. The optical servo writer further includes a fixed index and clock track circuit for providing a fix index and a clock signal for controlling the optical pickup head for writing the servo data on the optical flat data-storage medium. The optical servo writer further includes a head move circuit for controlling a movement of the optical pickup head for writing the servo data on the optical data-storage medium. The optical servo writer further includes a medium movement circuit for controlling a linear movement of the optical flat data-storage medium for writing the servo data on the optical flat data-storage medium.